<?php
/*===========================================================
= 版权协议：
= GPL (The GNU GENERAL PUBLIC LICENSE Version 2, June 1991)
=------------------------------------------------------------
= 文件名称：cls.sys_crypt.php
= 摘    要：php加密解密处理类
= 版    本：1.0
= 参    考：Discuz论坛的passport相关函数
=------------------------------------------------------------
= Script Written By PHPWMS项目组
= 最后更新：xinge
= 最后日期：2007-12-09
============================================================*/
namespace Think;
class SysCrypt {

    private $crypt_key;

    // 构造函数 
    public function __construct($crypt_key) {
       $this -> crypt_key = $crypt_key;
    }
    public function php_encrypt($txt) {
       srand((double)microtime() * 1000000);
       $encrypt_key = md5(rand(0,32000));
       $ctr = 0;
       $tmp = '';
       for($i = 0;$i<strlen($txt);$i++) {
        $ctr = $ctr == strlen($encrypt_key) ? 0 : $ctr;
        $tmp .= $encrypt_key[$ctr].($txt[$i]^$encrypt_key[$ctr++]);
       }
       return base64_encode(self::__key($tmp,$this -> crypt_key));
    }
    
    public function php_decrypt($txt) {
       $txt = self::__key(base64_decode($txt),$this -> crypt_key);
       $tmp = '';
       for($i = 0;$i < strlen($txt); $i++) {
        $md5 = $txt[$i];
        $tmp .= $txt[++$i] ^ $md5;
       }
       return $tmp;
    }
    
    private function __key($txt,$encrypt_key) {
       $encrypt_key = md5($encrypt_key);
       $ctr = 0;
       $tmp = '';
       for($i = 0; $i < strlen($txt); $i++) {
        $ctr = $ctr == strlen($encrypt_key) ? 0 : $ctr;
        $tmp .= $txt[$i] ^ $encrypt_key[$ctr++];
       }
       return $tmp;
    }
    
    public function __destruct() {
       $this -> crypt_key = null;
    }
}

/*
$sc = new SysCrypt('phpwms');
$text = '110';
print($sc -> php_encrypt($text));
print('<br>');
print($sc -> php_decrypt($sc -> php_encrypt($text)));
*/
?>
